U.S. patent number 4,954,465 [Application Number 07/295,754] was granted by the patent office on 1990-09-04 for apparatus for removing stink.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Miyakichi Kameda, Masaaki Kashiwabuchi, Masaei Kawashima, Reishi Naka, Syozo Ogawa, Nobuyoshi Suenaga, Koosuke Tanaka, Teruo Tsunoda.
United States Patent |
4,954,465 |
Kawashima , et al. |
September 4, 1990 |
Apparatus for removing stink
Abstract
A photocatalystic decomposing apparatus comprises absorbent
including honeycomb form active carbon and titanium oxide acting as
photocatalyst applied to a surface of the active carbon, and a
light source for generating ultraviolet rays exciting the
photocatalyst. Stink ingredient is absorbed to the active carbon by
passing air flow through openings in the honeycomb, and the
absorbed stink ingredient is decomposed by exciting the
photocatalyst due to application of the ultraviolet rays.
Inventors: |
Kawashima; Masaei
(Fujiokamachi, JP), Naka; Reishi (Ohiramachi,
JP), Tsunoda; Teruo (Ohiramachi, JP),
Suenaga; Nobuyoshi (Oyama, JP), Ogawa; Syozo
(Ohiramachi, JP), Kashiwabuchi; Masaaki (Tochigi,
JP), Kameda; Miyakichi (Sano, JP), Tanaka;
Koosuke (Ohiramachi, JP) |
Assignee: |
Hitachi, Ltd. (Tokyo,
JP)
|
Family
ID: |
26345902 |
Appl.
No.: |
07/295,754 |
Filed: |
January 11, 1989 |
Foreign Application Priority Data
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Jan 22, 1988 [JP] |
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63-10601 |
Jan 22, 1988 [JP] |
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63-10602 |
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Current U.S.
Class: |
502/5; 502/182;
502/417; 62/264; 502/183 |
Current CPC
Class: |
F25D
17/042 (20130101); B01D 53/8668 (20130101); B01D
53/86 (20130101); A61L 9/20 (20130101); B01D
2255/802 (20130101); F25D 2317/0417 (20130101); F25D
2317/0415 (20130101); F25D 2317/0681 (20130101) |
Current International
Class: |
B01D
53/86 (20060101); F25D 17/04 (20060101); B01J
037/34 () |
Field of
Search: |
;62/264
;502/5,182,183,417 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0125601 |
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Jul 1983 |
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JP |
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0203701 |
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Nov 1984 |
|
JP |
|
3078739 |
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Apr 1988 |
|
JP |
|
Primary Examiner: Capossela; Ronald C.
Attorney, Agent or Firm: Antonelli, Terry, Stout &
Kraus
Claims
What is claimed is:
1. A stink removing apparatus using absorbent, comprising a member
in which photocatalyst is applied on a surface of said absorbent
for absorbing stink ingredient or as mixed and kneaded with said
absorbent, said photocatalyst decomposing the stink ingredient
absorbed on said absorbent when excited by light and a light source
for exciting said photocatalyst.
2. A stink removing apparatus according to claim 1, wherein said
absorbent is formed as a honeycomb form, and said photocatalyst is
excited while passing air flow through apertures of the honeycomb
form.
3. A stink removing apparatus according to claim 1, wherein said
absorbent is formed as a honeycomb form, and the stink ingredient
is collected by absorbing it to said absorbent while passing air
flow through apertures of the honeycomb form, and said
photocatalyst is intermittently excited.
4. A stink removing apparatus according to claim 1, wherein said
absorbent comprises simple substance or composite of active carbon,
zeolite, porous ceramics or silica gel.
5. A stink removing apparatus according to claim 1, wherein said
photocatalyst comprises simple substance or composite of metallic
oxide such as titanium oxide, tungsten oxide, zinc oxide and the
like.
6. A stink removing apparatus according to claim 1, wherein the
photocatalyst having a particle diameter sufficiently larger than
pores in said absorbent is applied to the surface of said
absorbent.
7. A stink removing apparatus according to claim 1, wherein said
exciting source is arranged in the proximity of a high absorbing
density area of said absorbent.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for removing and
decomposing stink, and more particularly, it relates to an
apparatus for removing and decomposing stink which utilizes
absorbent having photocatalyst.
In a conventional stink removing apparatus, for example, as
disclosed in the Japanese Utility Model Laid Open Publication No.
47-22566, a casing containing absorbent such as active carbon was
inserted into an air flow passage, thereby removing stink
ingredient entrained by the air by absorbing it into the
absorbent.
As mentioned above, since the conventional stink removing apparatus
operates to remove the generated stink by absorbing it into the
absorbent such as the active carbon, there arose a problem that the
stink ingredient having high density could not be removed in a
short time. Further, since an amount of the stink ingredient
absorbed by the absorbent (i.e., holding ability of the absorbent)
is limited, it was necessary to replace or reproduce the absorbent
after it was used for a predetermined time period.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an apparatus for
removing stink, which can stably maintain an ability of removal of
stink for a long time by refleshing absorbent all the way.
The above-mentioned object is achieved by providing a layer of
photocatalyst, which can decompose stink ingredient sticked or
absorbed on the absorbent by the action of light, on a surface of
the absorbent, and by radiating exciting light (for exciting the
photocatalyst) onto the photocatalyst from a light source, and by
exciting the photocatalyst.
According to the stink removing apparatus of the present invention,
light having energy higher than that of a band gap of the
photocatalyst is radiated onto the photocatalyst provided on the
surface of the absorbent to excite the photocatalyst. Consequently,
decomposition of the stink ingredient is caused in the
photocatalyst so that the stink ingredient absorbed or sticked to
the absorbent is gradually decomposed and removed from a surface of
the absorbent. When the photocatalyst exciting light source
comprises a light source which hardly generates heat, the stink
ingredient is gradually decomposed and removed from the surface of
the absorbent mainly due to diffusion action caused by a difference
in density between an outer portion and an inner portion of the
absorbent. On the other hand, when the photocatalyst exciting light
source comprises a light source which generates heat, since the
absorbent is situated near the light source, the absorbent is
heated to reduce the holding ability thereof, thus releasing the
stink ingredient while decomposing it effectively by the
photocatalyst on the absorbent.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a stink removing apparatus
according to a preferred embodiment of the present invention;
FIG. 2 is a perspective view of a stink removing apparatus
according to another embodiment of the present invention;
FIG. 3 is an enlarged sectional view of a portion of the apparatus
of FIG. 1;
FIG. 4 is an explanatory view for explaining a principle of action
of photocatalyst;
FIG. 5 is a graph showing a feature for explaining the effect of
the preferred embodiment of the present invention;
FIG. 6 is a flow chart showing a process for manufacturing a
honeycomb form active carbon;
FIG. 7 is a flow chart showing a process for applying the
photocatalyst onto a surface of the honeycomb form active
carbon;
FIG. 8 is an exploded perspective view showing an example of a
concrete construction of the stink removing apparatus according to
the present invention;
FIG. 9 is a perspective view showing a main portion of the
apparatus of FIG. 8;
FIG. 10 is a longitudinal sectional view of the apparatus of FIG. 8
for explaining an air flow passing therethrough;
FIGS. 11 to 14 are perspective views showing other various forms or
shapes of the active carbon, respectively;
FIG. 15 is an explanatory view for explaining an operation of the
stink removing apparatus according to the present invention;
FIG. 16 is a perspective view of an embodiment of a light source
for exciting the photocatalyst;
FIG. 17 is a perspective view showing an example of a positional
relation between an aluminum reflector plate, the light source and
the active carbon;
FIG. 18 is a perspective sectional view of an embodiment of a
refrigerator incorporating the stink removing apparatus;
FIG. 19 is a sectional view showing a main portion of the
refrigerator incorporating the stink removing apparatus;
FIG. 20 is a sectional view for explaining how to attach the stink
removing apparatus to the refrigerator; and
FIG. 21 shows an embodiment of a control circuit for controlling
the operation of the refrigerator incorporating the stink removing
apparatus; and
FIG. 22 shows another embodiment of such control circuit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First of all, the present invention will be explained in connection
with a preferred embodiment thereof with reference to FIGS. 1 to
5.
An absorbent (for example, active carbon) 1 is configurated as a
honeycomb form to increase a surface area thereof, and thus has a
plurality of honeycomb form apertures 2. Photocatalyst 3 is
provided on a surface of the honeycomb form absorbent. The
photocatalyst 3 may be mixed and kneaded with the absorbent 1. In
this embodiment, an exciting source 4 for exciting the
photocatalyst comprises an ultraviolet ray lamp mounted on a socket
5. As shown in FIG. 2, the honeycomb form absorbent 1 may be
encircled by a buffer band 6 which may be made of, for example
sponge buffer material. When the absorbent is configurated in the
honeycomb form, since the periphery of the absorbent often becomes
fragile or brittle, the buffer band 6 may be arranged around the
absorbent to prevent the absorbent from damaging due to impact.
FIG. 3 is an enlarged view of a portion of FIG. 1, showing the
absorbent comprising the honeycomb form active carbon and particles
of the photocatalyst comprising metallic oxide existing on the
surface of the absorbent. In FIG. 3, a reference numeral 7
designates the active carbon as a base material for the absorbent,
which includes a plurality pores 7a, 7b and 7c each having a
dimension of the order of a few ten angstrom. A number of particles
8 of the photocatalyst are adhered to the surface of the active
carbon 7. Each of these particles normally has a diameter of the
order of a few hundred angstrom, and thus is larger than the
diameter of the pore 7a 7c in the active carbon by about ten times;
however, the particles are so selected as not to close or shut off
the pores in the active carbon.
Next, the action of the photocatalyst will be explained. The
photocatalyst is a substance which can convert photo energy into
chemical energy, and the particles of the metallic oxide
constituting the photocatalyst are semi-conductor and each has a
charged band E, a conductor band D, and a band gap G therebetween,
as shown in FIG. 4. The band gap has a value inherent to the
photocatalyst. For example, when the photocatalyst comprises
titanium dioxide, the band gap is 3 eV. When light having a
wavelength shorter than about 413 nm is applied onto the titanium
dioxide, electrons in the charged band E are flying onto the
conductor band D, thus creating positive holes h.sup.+ where the
electrons e.sup.- are left. This condition corresponds to an
excited condition of the photocatalyst. When the photocatalyst
comprises the titanium dioxide, such excited condition is created
as the ultraviolet rays (wavelength is 254 nm, input is 2 watts)
are applied onto the titanium dioxide.
OH-radical is generated from the surface of the photocatalyst or
semi conductor in such excited condition, as shown in the following
reaction formula: ##STR1## This OH-radical acts as active species
to oxidize and decompose the stink ingredient. In this case,
decomposible component in the stink ingredient is decomposed before
it is absorbed by the active carbon 7; on the other hand,
non-decomposible component (i.e., component slowly decomposed) in
the stink ingredient is absorbed by the active carbon and is
condensed therein, and thereafter, it is gradually decomposed from
the surface of the active carbon by the particles 8 of the
photocatalyst. Accordingly, it is effective to position a bright
point of the photocatalyst exciting light source in the proximity
of a position where density of absorbed stink ingredient on the
absorbent is the thickest or highest. For example, when the light
source is energized (applied) for 20-40 minutes, a distance between
the bright point of light and the absorbent may be about 1.5 cm-5
cm. Further, for example, when the stink ingredient, particularly
methyl mercaptan (CH.sub.3 SH) known as most bad smell ingredient
absorbed to the absorbent by a Van der Waals force is oxidized and
decomposed, the oxidation decomposition will be caused by the
following chemical reaction to eliminate the bad smell;
The other stink ingredients absorbed to the absorbent can also be
decomposed by an oxidation force of the OH radical to eliminate the
bad smell. FIG. 5 shows a test result obtained when anatase crystal
titanium oxide is used as the photocatalyst and the active carbon
is used as the absorbent. FIG. 5 shows residual rate of stink gas,
i.e., residual rate of dimethyl sulfide after the dimethyl sulfide
of 5 ppm is introduced in a container having an interior volume of
250 l and then the stink removing apparatus is driven. An abscissa
indicates "time" and an ordinate indicates "residual rate of stink
gas". A solid line A shows a feature of natural decay of the
dimethyl sulfide; a broken line B shows a feature of decay in the
case where the anatase crystal titanium oxide is applied to the
metal plate without using the absorbent and the ultraviolet rays
are applied thereon, and a two-dot chain line C shows the effect of
the present invention according to one embodiment thereof, that is,
shows a feature of decay in the case where the honeycomb form
active carbon is used as the absorbent and the anatase crystal
titanium oxide is applied to the surface of the active carbon and
the ultraviolet rays are applied thereon. As seen from the feature
of decay shown by the broken line B, the density of stink
ingredient can be reduced by decomposing the stink ingredient, even
when the photocatalyst is used alone. It has been found that, when
the absorbent was used, since the stink ingredient could be
collected to the absorbent and decomposed, the speed of
decomposition of the stink ingredient was increased. The
decomposition may be continuously performed by energizing the
ultraviolet ray lamp while providing the stink ingredient flow, or
may be intermittently performed by energizing the ultraviolet ray
lamp after the stink ingredient is collected to the absorbent
because the stink ingredient can be quickly collected by the Van
der Waals force of the absorbent. When the honeycomb form active
carbon is used as the absorbent (two-dot chain line C), since the
honeycomb active carbon does not include any organic bodies due to
high burning temperature thereof (about 1000.degree. C.), the
active carbon with the application of the ultraviolet rays can be
fully practically used.
FIG. 6 shows the manufacturing process for the honeycomb active
carbon. On the other hand, FIG. 7 shows a process for immersing the
honeycomb form active carbon into titania sol having the anatase
crystal (for example, solution of titanium dioxide having particle
diameter of about 50 nm and formed as sol condition) and then
applying anatase crystal titania particles (i.e., photocatalyst) to
the surface of the honeycomb form active carbon. The absorbent is
not limited to the honeycomb form active carbon, but may comprises
zeolite, porous ceramics, or silica gel as far as it has absorbing
ability. Similarly, the photocatalyst is not limited to the anatase
crystal titanium oxide, but may comprise simple substance or
composite of metallic oxide such as titanium oxide, tungsten oxide
or zinc oxide. The exciting source for exciting the photocatalyst
must provide the energy more than the band gap inherent to the
photocatalyst, as shown in the following Table 1:
TABLE 1 ______________________________________ Band Gap of Semi
conductor and Wavelength of Light corresponding thereto Excited
Wave- Semi-conductor Band Gap Energy length of Light
______________________________________ Titanium Oxide 3.0.sup.eV
413.sup.nm (TiO.sub.2) Tungsten Oxide 2.8 443 (Wo.sub.3) Di-iron
Trioxide 2.2 564 (Fe.sub.2 O.sub.3) Assenical Gallium 1.4 886
(GaAs) Molybdenum Sulfide 1.2 1033 (MoS.sub.2)
______________________________________
Since the removeal ability is more improved by increasing the
surface area of the absorbent, the configuration of the absorbent
may be sponge form, net form, concentric circular form, concentric
rectangular form or the like, other than the honeycomb form, and
may be suitably selected in accordance with equipments on which the
absorbent is mounted. Further, the particle diameter of the
photocatalyst applied on the surface of the absorbent not to reduce
the absorbing ability of the absorbent may be sufficiently larger
than the dimension of the pores in the absorbent.
Incidentally, the configuration of the absorbent is not limited to
the above-mentioned forms, but may be selected from any forms such
as fibre form, plate form, particle form or the like, as far as the
photocatalyst exciting light can be applied on the photocatalyst of
the absorbent. For example, the absorbent with the photocatalyst
may be net form one utilizing fibre active carbon as shown in FIG.
11, concentric circular form one as shown in FIG. 12, cylindrical
or prismatic form one having a plurality of through holes as shown
in FIG. 13, or concentric rectangular form one as shown in FIG. 14.
In these drawings, a reference numeral 22 designates a plurality of
through holes or openings, and 23 designates the absorbent with the
photocatalyst. When the absorbent is mounted on the stink removing
apparatus, the absorbents each having the same form or the
absorbent having the different forms selected from the above
mentioned forms such as the honeycomb form, net form, concentric
rectangular form and the like can be optionally used.
Further, when the metallic oxide such as the titanium oxide is used
as the photocatalyst, the photocatalyst can also be utilized as the
absorbent. That is to say, a porous molded product having the
absorbing ability can be obtained by burning and molding metallic
oxide which can constitute the photocatalyst. In this case, it
should be understood that there is no need to use the different
absorbent.
Now, FIG. 8 shows an example of a concrete construction of the
stink removing apparatus according to the present invention.
As shown in FIG. 8, the apparatus comprises a lower cover 101, an
intermediate partition 102 and an upper cover 103, which can be
made of plastic or metallic material and by which a body of the
stink removing apparatus is constituted. The stink ingredient is
passed through the apparatus by means of a blower fan 104. In this
way, the stink ingredient is absorbed and eliminated by the
apparatus. The apparatus also includes a photocatalyst exciting
light source such as an ultraviolet ray lamp 106, and an
ultraviolet reflecting plate 107 made of aluminum material. Arrows
shown in FIG. 8 indicate assembling directions in assembling the
elements as the stink removing apparatus. In the assembling
operation, first of all, pawls 52 formed on the intermediate
partition 102 are introduced into corresponding pawl receiver
openings 51 formed in the lower cover 101. Then, a stink removing
element 105 and the blower fan 104 are assembled to the
intermediate partition 102 and a fan motor 108, respectively.
Thereafter, the upper cover 103 is assembled to the lower cover
101. As shown in FIG. 9, the upper cover 103 is constituted by a
body of the upper cover 103d, a fan cover 103a, and a pre-filter
103b to improve molding ability and assembling ability. The body of
the upper cover 103d includes a plurality of intake openings 103c.
Arrows shown in FIG. 9 indicate assembling directions in assembling
the fan cover 103a and the pre-filter 103b into the body 103d of
the upper cover 103. The assembling operation is completed by
attaching the fan cover 103a to the upper cover body 103d through
pawls 34 and inserting the pre-filter 103b into the upper cover
body 103d.
Next, an air flow in the stink removing apparatus as constructed
above will be explained with reference to FIG. 10 showing a
longitudinal sectional view of the apparatus. In FIG. 10, arrows
indicate directions of the air flow which is flowing through an air
passage defined by plastic or metallic material. The air stream is
introduced from the intake openings 103c through the pre-filter
103b by rotating the blower fan 104 by means of a fan motor 108.
Thus, relatively large dust in the air stream is removed by the
pre-filter 103b. Thereafter, the air stream is passed through the
stink removing element (absorbent) 105, where the stink ingredient
in the air stream is removed, and then, the air stream is
discharged or exhausted from the fan cover 103a. Since the blower
fan 104 is constituted by an exhaust fan, the air stream introduced
through the intake openings 103c becomes a even flow, thus reducing
flowing resistance in comparison with that of air stream caused by
a forced draft fan. Further, since the blower fan 104 and fan motor
108 are spaced apart from the ultraviolet ray lamp 106, the fan 104
and fan motor 108 are not influenced upon heat and/or ultraviolet
rays from the lamp 106.
Next, the decomposing operation by means of the stink removing
apparatus according to the embodiment of the present invention will
be explained, on the basis of the air flow mentioned above, with
reference to FIG. 15 (where an abscissa indicates "time" and an
ordinate indicates "items" of operating elements or matters).
In FIG. 15, a indicates a starting for the blower fan; a time
interval between a and b corresponds to a period when the fan is
being operated and the absorbing action is effected; a time
interval between b and c corresponds to a period when the fan is
being stopped and the exciting light source is being energized; a
time interval between c and d is a period when the fan is being
operated again and the absorbing actions is effected again; and a
time interval between d and e is a period when the fan is being
stopped again and the exciting light source is being energized
again.
Normally, the stink ingredient is removed by being absorbed to the
absorbent while the air stream caused by the blower fan is made to
flow through the absorbent 105. Here, in order to clean the
absorbent in the following manner, the blower fan 104 is stopped
and the ultraviolet ray lamp 106 is energized. That is to say, the
stink ingredient absorbed by the honeycomb form active carbon is
gradually floated on the outer surface of the active carbon by the
heat as well as the ultraviolet rays generated by the ultraviolet
ray lamp 106. In this case, the photocatalyst on the surface of the
absorbent is in the excited condition by the application of the
ultraviolet rays. As an example, when the photocatalyst comprises
titanium dioxide, by applying the light having a wavelength of 420
nm or less (mainly, ultraviolet rays), the electrons in the charged
band are shifted to the conductor band, thus creating the positive
holes in the charged band, as previously stated. Due to such
bipolar condition, the chemical reaction is caused in the
photocatalyst, thereby decomposing the stink ingredient floated
from the honeycomb form active carbon. For example, the hydroxyl
group OH.sup.- existing on the surface of the photocatalyst is
changed to the OH radical by the above mentioned positive holes,
thereby creating the active species to decompose the stink
ingredient, with the result that the stink ingredient is changed to
low-molecular one to reduce the smell or stink, and thus, is
removed as a component which is not likely to be absorbed by the
honeycomb form active carbon. Incidentally, as stated above, by
stopping the blower fan 109 when the ultraviolet ray lamp 106 is
energized, it is possible to effectively make the stink ingredient
floated from the honeycomb form active carbon to be contact with
the photocatalyst. Further, when the blower fan 109 is stopped, the
heat from the ultraviolet ray lamp 106 can be effectively
transmitted to the photocatalyst, thus promoting the floating
action of the stink ingredient from the honeycomb form active
carbon. Further, since the stink ingredient is floated onto the
surface of the honeycomb active carbon due to diffusion when the
density of the stink ingredient around the surface of the active
carbon is lowered, the cleaning operation regarding the honeycomb
form active carbon can smoothly be performed.
While not shown in FIG. 15, the similar effect can be obtained by
energizing the exciting light source and the fan in synchronous
with each other to simultaneously energize the light source and the
fan whereby the absorbing action and the decomposing action are
simultaneously effected. For example, it is possible to
simultaneously energize the light source and the fan when the stink
removing apparatus is started to drive and to simultaneously
disenergize the light source and the fan when the apparatus is
stopped. Further, in the intermittent illumination of the light
source, it is possible to optionally select the time interval for
illuminating the light source so as to repeat the energization and
disenergization of the light source for a predetermined time
interval by using an appropriate timer, or to energize the light
source for a predetermined time interval once or twice a day.
Further, it is also possible to energize the light source, and
accordingly, to decompose the stink ingredient in synchronous with
a driving mode inherent to the equipments on which the stink
removing apparatus is mounted. For example, the stink removing
apparatus may be mounted in a refrigerator and the light source may
be energized in synchronous with a defrost action for periodically
removing the frost grown on a cooler disposed in the refrigerator.
Incidentally, when the light source is arranged in the proximity of
the absorbent, since the absorbent is heated immediately after the
light source is energized, the stink ingredient can be expelled
from the absorbent, thus enhancing the cleaning action for the
absorbent. According to the tests, it has been found that, when the
fan was stopped and the light source was energized, the temperature
of the absorbent was higher than the surrounding temperature by
about 10.degree. C. sufficient to expel the stink ingredient from
the absorbent due to the heat. When output of the light source is
increased, the more effective result can be obtained since the
temperature of the absorbent is still more increased.
FIG. 16 shows an example of the photocatalyst exciting light
source, which includes a small sized ultraviolet ray bulb lamp 106
mounted on a socket cover 106a which is made of porcelainous
material to prevent deterioration thereof due to the ultraviolet
rays.
FIG. 17 shows the positional relation between the absorbent element
105, the ultraviolet ray lamp 106 and the aluminum reflector plate
107. The positional relation is so selected that when the
ultraviolet lamp 106 is energized the radiated ultraviolet rays are
effectively applied onto the photocatalyst layer on the absorbent
105 and the upper and lower covers 101, 103 are least influenced
upon the ultraviolet rays. Incidentally, arrows in FIG. 17 show
adjustment of the position of the reflector plate 107.
According to this embodiment of the invention, since the absorbent
for absorbing the stink ingredient has the photocatalyst which is
applied onto the absorbent or is mixed and kneaded with the
absorbent, and the exciting light source for exciting the
photocatalyst is arranged in the proximity of the absorbent, the
absorbing speed, i.e., the stink removing speed due to the
absorbent can be increased, and the stink ingredient absorbed to
the absorbent can be continuously or intermittently decomposed due
to oxidization, and the absorbing ability of the absorbent can be
lengthened, thus providing a maintenance-free stink removing
apparatus. By using the simple substance or composite of the
metallic oxide such as the titanium oxide, tungsten oxide or zinc
oxide as the photocatalyst together with the absorbent, it is
possible to decompose the stink ingredient absorbed to the
absorbent by mere sunlight or normal visible light due to the
photocatalytic action of the metallic oxide. Accordingly, the stink
can be removed by the absorbent, and the absorbent having the
metallic oxide thereon can be refleshed by exposing it to the
sunlight or visible light, whereby the absorbent can be used
repeatedly (which was not impossible in the prior techniques).
Next, a concrete example that the stink removing apparatus so
constructed is mounted in the refrigerator will be explained.
FIG. 18 shows an example that the stink removing apparatus shown in
FIG. 8 is mounted in the refrigerator 60, where the stink removing
apparatus is designated by a reference numeral 100. The apparatus
100 is disposed at an upper portions of a face of an inner rear
wall 30 in a refrigerating room 62 of the refrigerator 60. With
this arrangement, the flow of air of which stink ingredient is
absorbed by the stink removing apparatus 100 will be as shown by
solid arrows in FIG. 18. On the other hand, the flow of cold air
from a cooler 65 caused by a refrigerator fan 15 disposed in a
freezing room 61 of the refrigerator 60 will be as shown by broken
arrows in FIG. 18. Since the air of which stink ingredient is
absorbed by the apparatus 100 is circulated in the refrigerating
room 62, the stink of the whole interior of the refrigerator 60 can
be removed.
Further, in FIG. 18, the refrigerator 60 includes a partition 63
for dividing the freezing room 61 from the refrigerating room 62,
which is made of heat-insulating material (for example, urethane)
and has a cold air passage 64 formed therein, and a food tray 70.
The cooler 65 may be, for example, constituted by cooling pipes and
cooling fins disposed between the pipes. While the stink removing
apparatus 100 shown in FIG. 18 includes the blower fan 104 (FIG.
20), as shown in FIG. 19, the stink removing apparatus 100 may be
constructed by utilizing the blown air from the refrigerator fan
15, such as a construction shown in a broken circle in FIG. 19. In
the refrigerator 60 shown in FIG. 19, the cold air generated by the
cooler 65 is circulated by the refrigerator fan 15 in the interior
of the refrigerator as shown by arrows in FIG. 19. The stink
removing apparatus 100 is arranged in the cold air passage 64
formed in the partition 63 for dividing the freezing room 61 from
the refrigerating room 62, with the result that the air is passed
through the apparatus 100 positively. Consequently, in this case, a
separate blower fan for the apparatus 100 can be omitted. The stink
removing apparatus 100 comprises a central ultraviolet ray lamp 106
acting as the photocatalyst exciting light source, fibre form
active carbon 55 arranged around the lamp, honeycomb active carbon
5 , and layers 5a of the photocatalyst formed on each active
carbon. Shield plates 56 and 57 for the ultraviolet rays are
disposed in an inlet and an outlet of the apparatus, respectively.
When the cold air flow is used alone without energizing the
ultraviolet ray lamp 106 acting as the photocatalyst exciting
source, the stink ingredient is absorbed to each active carbon 5b,
55 to remove stink. When the ultraviolet ray lamp 106 is energized,
the photocatalyst layers 5a are in the excited condition, thus
creating the decomposition of the stink ingredient as mentioned
above, thereby cleaning each active carbon 5b, 55. Incidentally,
when the ultraviolet ray lamp 106 is energized while permitting the
cold air flow, the stink ingredient in the air flow is
simultaneously decomposed while cleaning the active carbon.
As mentioned above, when the stink removing apparatus 100 is
constituted by utilizing the air flow caused by the refrigerator
fan 15, it is not necessary to dispose or arrange the apparatus 100
in the air passage 64 of the partition 63, but to arrange it at any
position where the air flow is created by the fan 15. Further, it
should be noted that it is not necessary to arrange the apparatus
100 through the whole cross-sectional area of the air passage 64 in
the partition 63 as shown in FIG. 19, but the apparatus 100 can be
arranged only in a part of the cross-sectional area of the passage
64.
FIG. 20 shows an example of a mounting method for mounting the
stink removing apparatus 100 shown in FIG. 18 in the refrigerator.
In FIG. 20, first of all, a fan motor 108 is fixed by means of the
lower and intermediate covers 101, 102 through rubber seats 50,
then the intermediate cover 102 is fixed to the lower cover 101 by
means of a setscrew 42 and the above mentioned pawls 52 (of the
intermediate cover 102) and receiver openings 51 (of the lower
cover). Thereafter, a pawl 31 formed on the outer surface of the
lower cover 101 is inserted into a pawl receiver 32 formed in the
inner wall 30 of the refrigerator and then the lower and
intermediate covers 101, 102 are fixed to the inner wall 30 of the
refrigerator by means of setscrews 41. Next, the absorbent 105 and
the blower fan 104 are attached to the intermediate cover 102 and
the fan motor 108, respectively. Thereafter, the body of the upper
cover 103d is mounted on the lower cover 101 and fixed thereto by
means of setscrews 43 and the pawl 33. Then, the fan cover 103a is
mounted on the upper cover body 103d through the pawl 34, and
lastly the pre-filter 103b is inserted into the upper cover body
103d, thus completing the assembling operation. Arrows in FIG. 20
show the assembling directions regarding the associated
elements.
An example of a control circuit for controlling the stink removing
apparatus is shown in FIG. 21. For simplicity's sake of
explanation, only the controlling operations required to perform
the stink decomposing operation will be explained herebelow. By
starting the stink removing apparatus by pushing a starter button
11, the operating command is transmitted to a control circuit 12,
thereby operating the stink removing apparatus. When the starter
button 11 is depressed, a stink removing operation displaying lamp
13 is illuminated to indicate that the stink removing apparatus
being operated.
The motor 108 for the blower fan 104 in the apparatus is controlled
by a signal emitted from an operation detector 14a of a compressor
14 in a freezing cycle (not shown) of the refrigerator, thereby
energizing a fan motor switch 21 when the compressor 14 is being
operated, thus driving the fan motor 108 to remove the stink in the
refrigerator. By such operation, the start-stop control for the fan
motor is performed, thus preventing the overheat of the fan motor
108 to lengthen its service life. When a door of the refrigerator
is opened, a motor 15M for the refrigerator fan 15 is stopped; the
opening and closing of the door are detected by a refrigerator fan
operation detector 15a, thus stopping the refrigerator fan 15 when
the door is being opened, regardless of the operation of the
compressor 14. With such arrangement, it is possible to minimize an
amount of cold air escaped out of the refrigerator when the door is
opened.
Further, a ultraviolet ray lamp 106 is operated and controlled as
follows. That is to say, after a defrosting heater 16 is energized
to perform the defrosting operation, when disenergization of the
defrosting heater 16 which is caused upon completion of the
defrosting operation is detected by a defrost detector 16a, the
ultraviolet ray lamp 106 is illuminated for a predetermined time
interval by energizing a lamp driving switch 22, and at the same
time the fan motor 108 is stopped by disenergizing the fan motor
switch 21, regardless of the operation of the compressor 14.
Accordingly, a defrost timer 16b can also act as a timer for the
stink removing apparatus, thus eliminating the necessity of the
provision of a separate timer for the apparatus.
After the predetermined time interval is elapsed, the ultraviolet
ray lamp 106 is disenergized, and the stink removing operation is
continued while controlling the operation of the blower fan of the
stink removing apparatus by detecting the operation of the
compressor 14 and the opening and closing of the door. When the
stink removing operation is not desired, the stink removing
apparatus may be stopped by disenergizing the starter button 11. In
this case, the displaying lamp 13 will be extinguished. A reference
numeral 17 designates a power source.
In this embodiment, normally, the stink removing operation is
performed by absorbing the stink ingredient by means of the
absorbent 5 while passing the air in the refrigerator through the
absorbent by means of the blower fan 104. However, when the blower
fan 104 is stopped and the ultraviolet ray lamp 106 is illuminated,
the cleaning operation of the absorbent is performed in the
following manner. That is to say, the stink ingredient absorbed to
the honeycomb form active carbon of the absorbent 105 is floated
gradually onto the surface of the active carbon due to the heat
from the ultraviolet ray lamp 106. In this case, the photocatalyst
disposed on the active carbon will be in the excited condition.
Incidentally, as stated above, when the blower fan motor 108 is
stopped while the ultraviolet ray lamp 106 being applied, it is
possible to effectively contact the stink ingredient floated on the
honeycomb form active carbon with the photocatalyst layer without
escape. Further, by stopping the blower fan motor 108 for the fan
104, the heat from the ultraviolet ray lamp 106 can effectively be
transmitted to the honeycomb form active carbon, thus promoting the
floating operation of the stink ingredient toward the surface of
the honeycomb form active carbon.
Further, when the density of the stink ingredient in the proximity
of the surface of the honeycomb form active carbon is decreased,
since the stink ingredient is shifted from inside to outside of the
active carbon due to the diffusion, the cleaning operation of the
honeycomb form active carbon can be performed more smoothly. The
time interval for applying the ultraviolet ray lamp 106 to carry
out the cleaning operation may be a time during when the honeycomb
form active carbon can decompose the stink ingredient absorbed
thereto between from one defrost operation to the next one.
Incidentally, it is preferable that the socket 106a (FIG. 16) is
positioned above the ultraviolet ray lamp 106 when installed in the
refrigerator so that even if the ultraviolet ray lamp is frosted
the water can effectively be prevented from dropping onto the
socket which may cause the deterioration of insulating feature of
the socket.
In the explanation mentioned above, while an example of the stink
removing operation controlled by the starter button was described,
the present invention is not limited to such example, but can be
applied to the case where the exciting light source is energized in
synchronous with the defrost of the cooler. FIG. 22 shows an
example of a control circuit used in such case. In FIG. 22, the
compressor 14 constituting a freezing cycle (not shown) is driven
by a temperature regulator 116. The motor 15M for the refrigerator
fan is driven in synchronous with the compressor 14. Incidentally,
the freezing cycle may include the compressor, cooler, condenser
and the like as already known. When a defrost timer 20 for the
cooler clocks for a predetermined time, it positively changes over
its contacts to supply voltage to a defrost heater H. The lamp 106
is connected in parallel to the heater H and is illuminated during
defrosting time (for example, 20-40 minutes). After the defrosting
operation is completed, voltage is applied to the defrost timer 20
again by separating contacts of a bimetal thermostat TH, and after
a predetermined time period the compressor 14 is activated. In this
case, the defrost timer 20 is connected in series to the parallel
circuit constituted by the defrost heater H and the lamp 106;
however, there arises no problem, since resistance of the defrost
heater H is considerably small in comparison with impedance of the
defrost timer 20. Door switches SW1 and SW2 associated with the
door of the refrigerator are connected in series to the fan motor
15M in such a manner that when the door is opened the fan motor 15M
is stopped. When a manual switch SW3 connected in series to the
motor 108 for the blower fan 104 is activated, the fan motor 108 is
driven in synchronous with the motor 15M. Accordingly, the lamp 106
decomposes the stink ingredient collected to the absorbent while
the refrigerator is used, i.e., the compressor 14 is driven,
regardless of the ON-OFF operation of the switch SW3.
According to the present invention, a stink removing apparatus for
a refrigerator, which maintains the stink removing ability
effectively for a long time, can be provided.
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